Non-Patent Document 1 discloses the concept of “group mobility”. This group mobility is a technology providing mobile communication services to user equipments in a conveyance by an on-board station arranged on the conveyance, in which the on-board station performs wireless communication with the user equipments in the conveyance and radio communication with a stationary base station outside the conveyance. The on-board station is a radio relay station and is also a base station for the user equipments in the conveyance. When the on-board station moves with the conveyance, the cell of the on-board station also moves. Even when the conveyance moves, the propagation condition of the radio waves between the on-board station and the user equipments in the conveyance is always stable.